1. Field of the Invention
This invention generally relates to a parking assistance device and a method for assisting a parking operation by controlling the steering assistant power.
2. Description of the Related Art
Conventionally, as a parking assistance device, xe2x80x9ca backward monitoring device of a vehiclexe2x80x9d is disclosed in a Japanese Patent Laid-Open Publication No. SHO. 59-114139, for example, which assists a parking operation using an image displayed on a screen. Namely, in such xe2x80x9ca backward monitoring device of a vehicle,xe2x80x9d marker position data corresponding to operational steering angle data of a vehicle tire are stored in advance, with regard to the backward direction of a driver""s own vehicle, marker position data corresponding to the operational steering angle data are retrieved and displayed on the screen of a monitor television that monitors the backward view of the driver""s own vehicle as a marker line in a duplicated way if the operational steering angle data are input from a tire directional sensor. Therefore, a marker, which is biased along a predicted backward trail of the driver""s own vehicle, as well as an obstacle is displayed on the screen of the monitor television nearby a seat of the driver""s own vehicle and the back ward direction of the driver""s own vehicle is clearly indicated, thus the load of such a parking operation as putting the vehicle into the garage and column parking can be reduced.
Further, as xe2x80x9ca vehicle electrical power steering device and an automatic operational devicexe2x80x9d disclosed in a Japanese Patent Laid-Open Publication No. HEI. 3-74256 and xe2x80x9csteering device and an automatic steering systemxe2x80x9d disclosed in a Japanese Patent Laid-Open Publication No. HEI. 4-55168, the load of the parking operation such as putting the vehicle into the garage and column parking can be reduced by controlling steering automatically.
However, in xe2x80x9ca backward monitoring device of a vehiclexe2x80x9d disclosed in the Japanese Patent Laid-Open Publication No. SHO. 59-114139, although marker, which is biased along the predicted backward trail of the driver""s own vehicle, as well as the obstacle is displayed on the screen of the monitor television nearby a seat of the driver""s own vehicle, the parking operation of the driver""s own vehicle along the predicted backward trail should be performed in the same way as a conventional parking operation. Thus, a problem in which the parking operation is influenced by a steering skill of a driver arises.
In xe2x80x9ca vehicle electrical power steering device and an automatic operational devicexe2x80x9d disclosed in the Japanese Patent Laid-Open Publication No. HEI. 3-74256 and xe2x80x9csteering device and an automatic steering systemxe2x80x9d disclosed in the Japanese Patent Laid-Open Publication No. HEI. 4-55168, although the parking operation of the driver""s own vehicle can be performed by controlling steering automatically, a problem, in which an avoidance operation to a sudden situation, for example, is delayed, has existed. For such a problem, although a consideration can be applied to such a sudden situation by releasing automatically a steering automatic control under a prescribed condition, in the case of the automatic steering control, a careless operation such as releasing a hand from steering is easily performed and thus a possibility in which an avoidance operation to a sudden situation is delayed surely exists.
Therefore, the present invention is made in order to solve the above-mentioned problem. The primary object, of the present invention is to provide a parking assistance device capable of parking the driver""s own vehicle easily along the parking course up to the parking target position.
Further, the secondary object of the present invention is to provide the steering operation for parking the vehicle which can be performed easily and further can manage the sudden situation at the time of performing a parking operation.
The present invention is a parking assistance device for calculating a parking course in which a driver""s own vehicle reaches a parking target position based on an image picturing a circumstantial view of the driver""s own vehicle, in which steering assistant power is increased if an operational steering angle changes towards a target rudder angle in order to move the driver""s own vehicle along the parking course and steering assistant power is decreased if an operational steering angle changes away from a target rudder angle.